scholarly journals Microglia Activation in the Brain as Inflammatory Biomarker of Alzheimer’s Disease Neuropathology and Clinical Dementia

2006 ◽  
Vol 22 (1-2) ◽  
pp. 95-102 ◽  
Author(s):  
Zhongmin Xiang ◽  
Vahram Haroutunian ◽  
Lap Ho ◽  
Dushant Purohit ◽  
Giulio Maria Pasinetti
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Molecular Layer ◽  
Neurofibrillary Tangle ◽  
Microglia Activation ◽  
Postmortem Brain ◽  
Neuritic Plaque ◽  
Clinical Dementia Rating ◽  
Inflammatory Biomarker ◽  
Hla Dr

The role of microglia-mediated inflammation in the progression of Alzheimer’s disease (AD) neuropathology remains unclear. In this study, postmortem brain sections from AD and control cases were subjected to Human Leukocyte Antigen (HLA)-DR immunohistochemistry to examine microglia activation in the progression of AD assessed by pre-mortem clinical dementia rating (CDR) and postmortem pathological manifestations of neuritic plaque (NP) and neurofibrillary tangle (NT) according to the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD). In both gray and white matter of the entorhinal cortex (EC) and HLA-DR immunostaining increased with the progression of CDR or CERAD NP, and to a lesser degree with CERAD NT. Between CDR stages HLA-DR significance was found in moderate (CDR 2) to severe dementia (CDR 5) where as between CERAD NP stages staining increased significantly from NP 0 (no plaque) to NP 1 (sparse plaques), suggesting increased microglia activation begins with amyloid NP deposition. In the hippocampus, a significant increase in microglia immunostaining was found in the pyramidal cell layer of CA1 as early as CDR 1, and in the upper molecular layer of the dentate gyrus in CDR 0.5. This increase continues with the progression of CDR and reaches maximum in CDR 5. When assessed by CERAD NP stages however, a significant increase in microglia immunostaining was found only in mid-to-late stages (NP 3) and reduced staining was seen in NP 5. These results suggest that microglia activation increases with the progression of AD, with the increase varying depending on the involved brain region.

Alzheimer’s Disease-Related Neuropathology Among Patients with Medication Treated Type 2 Diabetes in a Community-Based Autopsy Cohort

2021 ◽  
pp. 1-10
Author(s):  
Douglas Barthold ◽  
Laura E. Gibbons ◽  
Zachary A. Marcum ◽  
Shelly L. Gray ◽  
C. Dirk Keene ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Sex Education ◽  
Descriptive Analysis ◽  
Neurofibrillary Tangle ◽  
Apoe Genotype ◽  
Severity Index ◽  
Neuritic Plaque ◽  
Braak Stage ◽  
Total N

Background: Diabetes is a risk factor for Alzheimer’s disease and related dementias (ADRD). Epidemiologic evidence shows an association between diabetes medications and ADRD risk; cell and mouse models show diabetes medication association with AD-related neuropathologic change (ADNC). Objective: This hypothesis-generating analysis aimed to describe autopsy-measured ADNC for individuals who used diabetes medications. Methods: Descriptive analysis of ADNC for Adult Changes in Thought (ACT) Study autopsy cohort who used diabetes medications, including sulfonylureas, insulin, and biguanides; total N = 118. ADNC included amyloid plaque distribution (Thal phasing), neurofibrillary tangle (NFT) distribution (Braak stage), and cortical neuritic plaque density (CERAD score). We also examined quantitative measures of ADNC using the means of standardized Histelide measures of cortical PHF-tau and Aβ 1–42. Adjusted analyses control for age at death, sex, education, APOE genotype, and diabetes complication severity index. Results: Adjusted analyses showed no significant association between any drug class and traditional neuropathologic measures compared to nonusers of that class. In adjusted Histelide analyses, any insulin use was associated with lower mean levels of Aβ 1–42 (–0.57 (CI: –1.12, –0.02)) compared to nonusers. Five years of sulfonylureas and of biguanides use was associated with lower levels of Aβ 1–42 compared to nonusers (–0.15 (CI: –0.28, –0.02), –0.31 (CI: –0.54, –0.07), respectively). Conclusion: Some evidence exists that diabetes medications are associated with lower levels of Aβ 1–42, but not traditional measures of neuropathology. Future studies are needed in larger samples to build understanding of the mechanisms between diabetes, its medications, and ADRD, and to potentially repurpose existing medications for prevention or delay of ADRD.

scholarly journals EDITORIAL: BLOOD TESTS FOR ALZHEIMER’S DISEASE AND RELATED DISORDERS

2019 ◽  
pp. 1-2
Author(s):  
E.M. Reiman
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Task Force ◽  
Neurofibrillary Tangle ◽  
Neuritic Plaque ◽  
Plaque Burden ◽  
Neurofilament Light ◽  
Task Force Report ◽  
Blood Tests ◽  
Wide Range

This issue of the Journal of Prevention of Alzheimer’s Disease (AD) includes a timely Clinical Trials on AD Task Force Report on promising blood tests for AD and related disorders (1). It highlights the promise of recently developed plasma amyloid-β42/40 (Aβ42/40) measurements for the assessment of neuritic plaque burden (e.g., reference 2), ultrasensitive neurofilament light (NfL) measurements for the assessment of ongoing neuroaxonal injury in a wide range of neurological disorders (3), and their potential roles in evaluation of interventions to treat and prevent the clinical onset of AD. It also considers recently developed plasma total-tau measurements, an indicator of neuronal injury and/or Aβ-mediated tau secretion (4), plasma phospho-tau measurements, a potential indicator of neurofibrillary tangle burden, and the ongoing effort to develop high-dimensional plasma genomic, transcriptomic, metabolomic, lipidomic, and proteomic profiles.

scholarly journals Phosphorylated tau fluid biomarker sites recognize earlier neurofibrillary tangle maturity levels in the postmortem Alzheimer’s disease brain

2021 ◽  
Author(s):  
Christina M. Moloney ◽  
Sydney A. Labuzan ◽  
Julia E. Crook ◽  
Habeeba Siddiqui ◽  
Monica Castanedes-Casey ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurofibrillary Tangle ◽  
Global Scale ◽  
Postmortem Brain ◽  
Braak Stage ◽  
Phosphorylated Tau ◽  
Regional Vulnerability ◽  
Early Fluid ◽  
Fluid Biomarker

AbstractAlzheimer’s disease (AD) biomarkers have become increasingly more reliable in predicting AD pathology. While phosphorylated tau fluid biomarkers have been studied for over 20 years, there is a lack of deep characterization of these sites in the postmortem brain. Neurofibrillary tangle-bearing neurons, one of the major neuropathologic hallmarks of AD, undergo morphologic changes that mature along a continuum as hyperphosphorylated tau aggregates. To facilitate interpretation of phosphorylated tau sites as an early fluid biomarker, our goal was to characterize which neurofibrillary tangle maturity levels (pretangle, intermediary 1, mature tangle, intermediary 2, and ghost tangle) they recognize. We queried the Florida Autopsied Multi-Ethnic (FLAME) cohort for cases from Braak stages I-VI. We excluded non-AD pathologies and tauopathies. A total of 24 cases, 2 males and 2 females for each Braak stage, were selected. We performed immunohistochemistry on the posterior hippocampus using antibodies directed towards phospho (p) threonine (T) 181, pT205, pT217, and pT231. Slides were digitized to enable quantification of tau burden. To examine differences in regional vulnerability between CA1 and subiculum, we developed a semi-quantitative system to rank the frequency of each neurofibrillary tangle maturity level. We identified all neurofibrillary tangle maturity levels at least once for each phosphorylated tau site. Primarily earlier neurofibrillary tangle maturity levels (pretangle, intermediary 1, mature tangle) were recognized for all phosphorylated tau sites. There was an increase in tau burden in the subiculum compared to CA1; however, this was attenuated compared to thioflavin-S positive tangle counts. On a global scale, tau burden generally increased with each Braak stage. These results provide neurobiologic evidence that these phosphorylated tau fluid biomarker sites are present during earlier neurofibrillary tangle maturity levels. This may help explain why these phosphorylated tau biomarker sites are observed before symptom onset in fluids.

scholarly journals Tau-mediated Disruption of the Spliceosome Triggers Cryptic RNA-splicing and Neurodegeneration in Alzheimer’s Disease

2019 ◽  
Author(s):  
Yi-Chen Hsieh ◽  
Caiwei Guo ◽  
Hari K. Yalamanchili ◽  
Measho Abreha ◽  
Rami Al-Ouran ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Rna Splicing ◽  
Intron Retention ◽  
Neurofibrillary Tangle ◽  
Neuronal Loss ◽  
Mrna Splicing ◽  
Postmortem Brain ◽  
Loss Of Function ◽  
Human Postmortem Brain

SUMMARYIn Alzheimer’s disease (AD), spliceosomal proteins with critical roles in RNA processing aberrantly aggregate and mislocalize to Tau neurofibrillary tangles. We test the hypothesis that Tau-spliceosome interactions disrupt pre-mRNA splicing in AD. In human postmortem brain with AD pathology, Tau coimmunoprecipitates with spliceosomal core components. In Drosophila models, pan-neuronal Tau expression triggers reductions in core and U1-specific spliceosomal proteins, and genetic disruption of these factors, including SmB, U1-70K, and U1A, enhances Tau-mediated neurodegeneration. We further show that loss-of-function in SmB, encoding a core spliceosomal protein, causes decreased survival, progressive locomotor impairment, and neuronal loss, independent of Tau toxicity. Lastly, RNA-sequencing reveals a similar profile of mRNA splicing errors in SmB mutant and Tau transgenic flies, including intron retention and non-annotated cryptic splice junctions. In human brains, we confirm cryptic splicing errors in association with neurofibrillary tangle pathologic burden. Our results implicate spliceosome disruption and perturbations of the neuronal transcriptome in Tau-mediated neurodegeneration in AD.

scholarly journals Stages of Objective Memory Impairment Predict Alzheimer’s Disease Neuropathology: Comparison with the Clinical Dementia Rating Scale–Sum of Boxes

2021 ◽  
pp. 1-11
Author(s):  
Ellen Grober ◽  
Qi Qi ◽  
Lynn Kuo ◽  
Jason Hassenstab ◽  
Richard J. Perrin ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Logistic Regression ◽  
Memory Impairment ◽  
Rating Scale ◽  
Neurofibrillary Tangle ◽  
Staging System ◽  
Braak Stage ◽  
Operating Characteristics ◽  
Clinical Dementia Rating

Background: The ultimate validation of a clinical marker for Alzheimer’s disease (AD) is its association with AD neuropathology. Objective: To examine how well the Stages of Objective Memory Impairment (SOMI) system predicts intermediate/high AD neuropathologic change and extent of neurofibrillary tangle (NFT) pathology defined by Braak stage, in comparison to the Clinical Dementia Rating (CDR) Scale sum of boxes (CDR-SB). Methods: 251 well-characterized participants from the Knight ADRC clinicopathologic series were classified into SOMI stage at their last assessment prior to death using the free recall and total recall scores from the picture version of the Free and Cued Selective Reminding Test with Immediate Recall (pFCSRT + IR). Logistic regression models assessed the predictive validity of SOMI and CDR-SB for intermediate/high AD neuropathologic change. Receiver operating characteristics (ROC) analysis evaluated the discriminative validity of SOMI and CDR-SB for AD pathology. Ordinal logistic regression was used to predict Braak stage using SOMI and CDR-SB in separate and joint models. Results: The diagnostic accuracy of SOMI for AD diagnosis was similar to that of the CDR-SB (AUC: 85%versus 83%). In separate models, both SOMI and CDR-SB predicted Braak stage. In a joint model SOMI remained a significant predictor of Braak stage but CDR-SB did not. Conclusion: SOMI provides a neuropathologically validated staging system for episodic memory impairment in the AD continuum and should be useful in predicting tau positivity based on its association with Braak stage.

Psychotic Symptoms in Alzheimer's Disease Are Not Associated With More Severe Neuropathologic Features

2000 ◽  
Vol 12 (4) ◽  
pp. 547-558 ◽  
Author(s):  
Robert A. Sweet ◽  
Ronald L. Hamilton ◽  
Oscar L. Lopez ◽  
William E. Klunk ◽  
Stephen R. Wisniewski ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Functional Decline ◽  
Neurofibrillary Tangle ◽  
Temporal Cortex ◽  
Lewy Bodies ◽  
Occipital Cortex ◽  
Brain Regions ◽  
Neuritic Plaque ◽  
Psychotic Symptoms

Psychotic symptoms in Alzheimer's disease (AD) have been associated with increased rates of cognitive impairment and functional decline. Prior studies have been conflicting with regard to whether AD patients with psychosis (AD+P) have evidence of more severe neuropathologic findings at postmortem exam. We examined the severity of neuritic plaques and neurofibrillary tangles in six brain regions—middle frontal cortex, hippocampus, inferior parietal cortex, superior temporal cortex, occipital cortex, and transentorhinal cortex—in 24 AD+P subjects and 25 matched AD subjects without psychosis (AD-P). All analyses controlled for the presence of cortical Lewy bodies, and corrected for multiple comparisons. We found no significant associations between neuritic plaque and neurofibrillary tangle severity and AD+P, and no significant associations with any individual psychotic symptom. The association of AD+P with a more rapidly progressive course of AD appears to be mediated by a neuropathologic process other than increased severity of plaque and tangle formation.

Computer-aided methods for 3-D visualization of serial sections and thick biological specimens

1992 ◽  
Vol 50 (2) ◽  
pp. 1060-1061
Author(s):  
Mark Ellisman ◽  
Maryann Martone ◽  
Gabriel Soto ◽  
Eleizer Masliah ◽  
David Hessler ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Three Dimensional ◽  
Neuritic Plaque ◽  
Dimensional Structure ◽  
Data Sets ◽  
Molecular Physiology ◽  
Research Activities ◽  
Computer Aided ◽  
Dimensional Reconstruction

Structurally-oriented biologists examine cells, tissues, organelles and macromolecules in order to gain insight into cellular and molecular physiology by relating structure to function. The understanding of these structures can be greatly enhanced by the use of techniques for the visualization and quantitative analysis of three-dimensional structure. Three projects from current research activities will be presented in order to illustrate both the present capabilities of computer aided techniques as well as their limitations and future possibilities.The first project concerns the three-dimensional reconstruction of the neuritic plaques found in the brains of patients with Alzheimer's disease. We have developed a software package “Synu” for investigation of 3D data sets which has been used in conjunction with laser confocal light microscopy to study the structure of the neuritic plaque. Tissue sections of autopsy samples from patients with Alzheimer's disease were double-labeled for tau, a cytoskeletal marker for abnormal neurites, and synaptophysin, a marker of presynaptic terminals.

scholarly journals Disruption of a RAC1-centred network is associated with Alzheimer’s disease pathology and causes age-dependent neurodegeneration

2020 ◽  
Vol 29 (5) ◽  
pp. 817-833 ◽  
Author(s):  
Masataka Kikuchi ◽  
Michiko Sekiya ◽  
Norikazu Hara ◽  
Akinori Miyashita ◽  
Ryozo Kuwano ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Genetic Model ◽  
Neurofibrillary Tangle ◽  
Neuronal Cell ◽  
Brain Regions ◽  
Protein Domain ◽  
Expression Data ◽  
Integrated Network ◽  
Age Dependent

Abstract The molecular biological mechanisms of Alzheimer’s disease (AD) involve disease-associated crosstalk through many genes and include a loss of normal as well as a gain of abnormal interactions among genes. A protein domain network (PDN) is a collection of physical bindings that occur between protein domains, and the states of the PDNs in patients with AD are likely to be perturbed compared to those in normal healthy individuals. To identify PDN changes that cause neurodegeneration, we analysed the PDNs that occur among genes co-expressed in each of three brain regions at each stage of AD. Our analysis revealed that the PDNs collapsed with the progression of AD stage and identified five hub genes, including Rac1, as key players in PDN collapse. Using publicly available as well as our own gene expression data, we confirmed that the mRNA expression level of the RAC1 gene was downregulated in the entorhinal cortex (EC) of AD brains. To test the causality of these changes in neurodegeneration, we utilized Drosophila as a genetic model and found that modest knockdown of Rac1 in neurons was sufficient to cause age-dependent behavioural deficits and neurodegeneration. Finally, we identified a microRNA, hsa-miR-101-3p, as a potential regulator of RAC1 in AD brains. As the Braak neurofibrillary tangle (NFT) stage progressed, the expression levels of hsa-miR-101-3p were increased specifically in the EC. Furthermore, overexpression of hsa-miR-101-3p in the human neuronal cell line SH-SY5Y caused RAC1 downregulation. These results highlight the utility of our integrated network approach for identifying causal changes leading to neurodegeneration in AD.

scholarly journals Autoregulation of Cerebral Blood Flow to Changes in Arterial Pressure in Mild Alzheimer's Disease

2010 ◽  
Vol 30 (11) ◽  
pp. 1883-1889 ◽  
Author(s):  
Allyson R Zazulia ◽  
Tom O Videen ◽  
John C Morris ◽  
William J Powers
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Arterial Pressure ◽  
The Elderly ◽  
Local Defect ◽  
Clinical Dementia Rating ◽  
Positron Emission ◽  
Before And After

Studies in transgenic mice overexpressing amyloid precursor protein (APP) demonstrate impaired autoregulation of cerebral blood flow (CBF) to changes in arterial pressure and suggest that cerebrovascular dysfunction may be critically important in the development of pathological Alzheimer's disease (AD). Given the relevance of such a finding for guiding hypertension treatment in the elderly, we assessed autoregulation in individuals with AD. Twenty persons aged 75±6 years with very mild or mild symptomatic AD (Clinical Dementia Rating 0.5 or 1.0) underwent 15O-positron emission tomography (PET) CBF measurements before and after mean arterial pressure (MAP) was lowered from 107±13 to 92±9 mm Hg with intravenous nicardipine; 11C-PIB-PET imaging and magnetic resonance imaging (MRI) were also obtained. There were no significant differences in mean CBF before and after MAP reduction in the bilateral hemispheres (−0.9±5.2 mL per 100 g per minute, P=0.4, 95% confidence interval (CI)=−3.4 to 1.5), cortical borderzones (−1.9±5.0 mL per 100 g per minute, P=0.10, 95% CI=−4.3 to 0.4), regions of T2W-MRI-defined leukoaraiosis (−0.3±4.4 mL per 100 g per minute, P=0.85, 95% CI=−3.3 to 3.9), or regions of peak 11C-PIB uptake (−2.5±7.7 mL per 100 g per minute, P=0.30, 95% CI=−7.7 to 2.7). The absence of significant change in CBF with a 10 to 15 mm Hg reduction in MAP within the normal autoregulatory range demonstrates that there is neither a generalized nor local defect of autoregulation in AD.

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